Well, i'm not sure how many cornell people are still around on the boards, but if you do a search you should find some good responses from the previous years. I'm a current MS2, so i'll give you some of my opinions, in brief:
Student life: really good!! You have a decent amount of time during the first semester to really enjoy the city, and even after that, since everything is so close, lots of people regularly go out and do stuff. We even have some outdoorsy types (myself included) that although are a bit stymied by lack of nearby skiing, etc., still have ice skating rinks, central park, etc., to enjoy. Lot of museums, theaters, and so on - obviously, because it's NYC. Also, we're located in a very safe neighborhood, so you can go out pretty much whenever.
Professors: can be good or bad, depending on the class. Overall, our anatomy/physiology course and neuro courses are outstanding - i really do think we have some of the best profs in those departments. It doesn't really matter though, because every school has good/bad profs; we get full transcripts and slides for every lecture (they're also online), so you can really learn the material just that way if you wanted. Or use the review books.
Classes: again, good and bad. First year, we have three main 'modules'; the first is biochem/genetics, etc.; the second is anatomy/physiology, and the last one is micro/immuno. The first one is kind of sucky, but the second two are great. Second year we have two courses, neuro/psych, which is absolutely outstanding, and pathology, which is pretty good so far (we're only in the third week). You can get all of the details from the website, so i'd say read that and then post if you have specific questions.
By the way - Cornell is very strong in international medicine; we have a very active student organization, about 16/100 people went abroad during the first summer (we get $$ from the school to go!) and we sponsor a lot of international research, electives, etc. So if you're into that, this is the place to come.
I graduated not long ago, and had a great time there. I'll try not to be redundant, since I "Agree with MS2 note".
First two years are easy and with loads of free time. Class time is half PBL half lecture, with one day each week dedicated to clinical experience. You have plenty of time to study and plenty of time to enjoy the park, and the rest of the city. When anatomy starts in January things get a bit busier. Lectures are hit or miss as described, probably the same calibre as other schools - you get a lot of physician scientists who deliver powerpoint lectures that miss the mark, but you also get a lot of spot-on lectures from faculty who clearly take the time to teach, and enjoy it.
Class sizes are small so cameraderie can be good or bad. For my class it was good. Cornell lore is that every other year the class loves each other, but the in between years it hates each other. I have some really great friends from med school, and 8 of us are engaged to other former classmates.
The third and fourth years are awesome. By design, we rotate through hospitals all over the city -- our own, as well as hospitals in Brooklyn, Queens and the Bronx. Patient population is as varied as the city offers. The workload is intense and the hours can be brutal, but that's what you signed up for, after all! You do spend quite a bit of time doing hospital chores, eg, phlebotomy, IVs, etc, but this all comes in handy intern year. You tend to get lectures every day, most of the time these are good.
Last thing, I have to second what the med student said about international medicine. I spent the summer after first year in Cuba working in an OR, I spent the second half of fourth year back in Latin America and also in the UK. All fully funded.